The present application relates generally to marine propellers and, more particularly, to propellers of the type which have shock absorbing hubs.
Propellers used in many inboard and outboard pleasure boats are mounted on the splined drive shaft of the engine by a hub having a rubber shock absorbing element which dampens sudden changes in rotational torque applied to the propeller or the shaft, such as upon changing between forward and reverse directions or upon the propeller striking an obstruction.
In many conventional propellers, the shock absorbing hub commonly is permanently press fit into a blade-supporting propeller housing, such as by use of a high tonnage press, so as to insure that the propeller housing will be maintained in proper torque-transmitting relation with the hub. When the propeller is damaged, as frequently occurs in pleasure boating activities, the entire propeller housing and hub assembly must be removed in order to effect repair or replacement. This first requires removing a retaining nut assembly from the drive shaft. In instances where efforts are made to make such repair or replacement when the boat remains in open water, it is easy to drop the nut or associated washers and lose those components in the water. Repair of the propeller can be costly, and because of the relative complexity of propellers with such shock absorbing mountings, it commonly has not been economical to maintain a replacement propeller on board recreational and pleasure boats.
Apart from the problem of replacing damaged propellers, boat owners often desire to selectively use propellers with differently pitched blades for particular boating uses. For example, a propeller having blades of one pitch may be desirable for pleasure cruising while a propeller with blades of a significantly different pitch is preferred for water skiing. Heretofore, the significant cost of extra propellers, as well as the inconvenience of changing propellers, has impeded boat owners from being able to selectively utilize the optimum propeller for particular boat usage.